When blood supply to the heart is restricted because of narrowing of the coronary arteries, myocardial ischemia develops which is often not accompanied by chest pain. These episodes can be measured by continuous monitoring of the ECG by using the Holter monitor. Although much information is available about the occurrence of ischemia in male patients with coronary artery disease, whether female patients have differences compared to males has not been studied. We have performed Holter monitoring in 25 women with coronary artery disease and measured the frequency and distribution of the ischemic episodes according to time of day, and the heart rate at which these episodes occur and compared them against male patients. The circadian variation in ischemic episodes with a morning surge, a daytime plateau and a nighttime trough is similar in female patients as male. Ischemia develops at a lower heart rate in the early morning hours compared to other times of the day. This is again similar to male patients.